The purpose of the invention is mainly to provide a device including a radial combiner for electromagnetic waves and a method using a radial combiner.
The use of the radial combiner of the present invention makes it possible to modulate the signal to be transmitted in amplitude and/or in phase by phase modulating the different amplifiers or transmitters connected in said combiner.
With the lowering of prices and improvement of the performances of semiconductor devices, they can replace tube devices even in the fields which up to now were reserved for tubes. This is particularly true in electromagnetic wave transmitters, particularly for radio broadcasting, television broadcasting or radar.
For these applications, a plurality of transistorized amplifiers or transmitters is often used coupled to a single antenna, each transmitter delivering a part of the total radiated power. The assembly of the plurality of transmitters poses problems of space as well as coupling the transmitters to the antenna.
One of the advantages of using a plurality of transmitters is to be able to continue operation despite a breakdown of some transmitters. The radial combiner used in the device of the present invention includes resistors for absorbing the energy likely to disturb the operation of the device in the case of a breakdown of certain transmitters.
The modulation of class B or C transistorized amplifiers is more difficult than that using tubes, for example of the Klystron type. This drawback is particularly important at low amplitude. In fact, the transistorized amplifiers or transmitters operating in class B or C only deliver an output power above a threshold. The transition about the threshold is abrupt generating a secondary frequency lobe spectrum of high amplitude. In addition, it is not possible to modify the shape of the pulses emitted using such transmitters by modulating the input signal.
In the device of the present invention, the phase variation caused by some transmitters connected to the input of a radial combiner makes it possible to obtain constructive or destructive interferences during the combination of the signal. Thus, depending on the value of the phase shifts applied, it is possible to obtain different amplitudes. It is thus possible in particular to modify the shape of the transmitted pulse, for example for minimizing the secondary frequency lobes generated by these pulses.